Systems and methods for pulsed-wave lidar

ABSTRACT

In some implementations, a light detection and ranging (LIDAR) system includes a laser source configured to provide an optical signal at a first signal power, an amplifier having a plurality of gain levels, at which the amplifier is configured to amplify the optical signal, and one or more processors. The one or more processors are configured to, based on the first signal power and a duty cycle of the optical signal, vary a gain level of the amplifier from the plurality of gain levels to generate a pulse signal, transmit the pulse signal from the amplifier to an environment, receive a reflected signal that is reflected from an object, responsive to transmitting the pulse signal, and determine a range to the object based on an electrical signal associated with the reflected signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/329,413, filed on May 25, 2021, which claims the benefit of andpriority to U.S. patent application Ser. No. 16/917,297, filed Jun. 30,2020. The entire disclosure of U.S. patent application Ser. No.16/917,297 and U.S. patent application Ser. No. 17/329,413 isincorporated herein by reference.

BACKGROUND

Optical detection of range using lasers, often referenced by a mnemonic,LIDAR, for light detection and ranging, also sometimes called laserRADAR, is used for a variety of applications, from altimetry, toimaging, to collision avoidance. LIDAR provides finer scale rangeresolution with smaller beam sizes than conventional microwave rangingsystems, such as radio-wave detection and ranging (RADAR). Opticaldetection of range can be accomplished with several differenttechniques, including direct ranging based on round trip travel time ofan optical pulse to an object, and chirped detection based on afrequency difference between a transmitted chirped optical signal and areturned signal scattered from an object, and phase-encoded detectionbased on a sequence of single frequency phase changes that aredistinguishable from natural signals.

SUMMARY

Aspects of the present disclosure relate generally to light detectionand ranging (LIDAR) in the field of optics, and more particularly tosystems and methods for pulsed-wave LIDAR to support the operation of avehicle.

One implementation disclosed here is directed to a LIDAR system. TheLIDAR system includes a laser source configured to provide an opticalsignal. In some implementations, the LIDAR system includes an amplifier(e.g., an erbium doped fiber amplifier (EDFA) or a semiconductor opticalamplifier (SOA)) having a plurality of gain configurations, wherein theamplifier is configured to receive the optical signal, and amplify theoptical signal based on a gain configuration of the plurality of gainconfigurations. In some implementations, the LIDAR system includes oneor more processors configured to adjust the gain configuration of theamplifier across two or more of the plurality of gain configurations tocause the amplifier to generate an amplified signal corresponding to apulse envelope signal.

In another aspect, the present disclosure is directed to a LIDAR system.The LIDAR system includes a laser source configured to provide anoptical signal. In some implementations, the LIDAR system includes anoptical switch having a first terminal, a second terminal, and a switchmode. In some implementations, the optical switch is configured toreceive the optical signal at the first terminal; responsive to theoptical switch being configured in the first mode, allow a transmissionof the optical signal from the first terminal to the second terminal,responsive to the optical switch being configured in the second mode,block the transmission of the optical signal to the second terminal. Insome implementations, the LIDAR system includes one or more processorsconfigured to change the optical switch mode between the first mode andthe second mode to cause the optical switch to generate a pulse envelopesignal.

In another aspect, the present disclosure is directed to a LIDAR system.The LIDAR system includes a laser source configured to provide anoptical signal. In some implementations, the LIDAR system includes apulse envelope generator configured to generate a pulse envelope signalby determining a relative phase difference between a first opticalsignal associated with the optical signal and a second optical signalassociated with the optical signal, or modulating the light signal usingan electrical field. In some implementations, the LIDAR system includesan amplifier configured to amplify the pulse envelope signal andtransmit the amplified pulse envelope signal via one or more opticalelements.

In another aspect, the present disclosure is directed to a method forpulsed-wave LIDAR to support the operation of a vehicle. In someimplementations, the method includes modulating an optical signal togenerate a modulated optical signal. In some implementations, the methodincludes selecting a plurality of pulses from the modulated opticalsignal to generate a pulsed envelope signal. In some implementations,the method includes transmitting the pulsed envelope signal via one ormore optical elements. In some implementations, the method includesreceiving a reflected signal responsive to transmitting the pulsedenvelope signal. In some implementations, the method includesdetermining a range to an object based on an electrical signalassociated with the reflected signal.

Still other aspects, features, and advantages are readily apparent fromthe following detailed description, simply by illustrating a number ofparticular implementations, including the best mode contemplated forcarrying out the invention. Other implementations are also capable ofother and different features and advantages, and their several detailscan be modified in various obvious respects, all without departing fromthe spirit and scope of the invention. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive.

BRIEF DESCRIPTION OF THE FIGURES

Implementations are illustrated by way of example, and not by way oflimitation, in the figures of the accompanying drawings in which likereference numerals refer to similar elements and in which:

FIG. 1A is a block diagram illustrating an example of a systemenvironment for autonomous vehicles according to some implementations;

FIG. 1B is a block diagram illustrating an example of a systemenvironment for autonomous commercial trucking vehicles, according tosome implementations;

FIG. 1C is a block diagram illustrating an example of a systemenvironment for autonomous commercial trucking vehicles, according tosome implementations;

FIG. 1D is a block diagram illustrating an example of a systemenvironment for autonomous commercial trucking vehicles, according tosome implementations;

FIG. 2 is a time-based graph depicting the differences (e.g.,differences in amplitude, period, average power, duty cycle, etc.)between the waveforms produced by one or more LIDAR systems that use CWoperation, quasi-CW operation, and/or pulsed-wave operation;

FIG. 3A is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an EDFA for operating anautonomous vehicle, according to some implementations;

FIG. 3B is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an EDFA and directlymodulating a laser source for operating an autonomous vehicle, accordingto some implementations;

FIG. 3C illustrates an example waveform of the optical intensity beforean EDFA, where the EDFA has a constant pumping rate of gain, accordingto some implementations;

FIG. 3D illustrates an example waveform of the optical intensity afteran EDFA, where the EDFA has a constant pumping rate of gain, accordingto some implementations;

FIG. 4A is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an optical switch foroperating an autonomous vehicle, according to some implementations;

FIG. 4B is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an optical switch foroperating an autonomous vehicle, according to some implementations;

FIG. 4C is a flow chart that illustrates an example method forpulsed-wave LIDAR to support the operation of a vehicle, according to animplementation;

FIG. 5 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using a Mach-Zehnder modulator foroperating an autonomous vehicle, according to some implementations;

FIG. 6 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using an electro-absorption modulator(EAM) for operating an autonomous vehicle, according to someimplementations;

FIG. 7 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using a semiconductor optical amplifier(SOA) for operating an autonomous vehicle, according to someimplementations; and

FIG. 8 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using a semiconductor optical amplifier(SOA) and index modulation for operating an autonomous vehicle,according to some implementations.

DETAILED DESCRIPTION

A LIDAR system may include a transmit (Tx) path and a receive (Rx) path.The transmit (Tx) path may include a laser source for providing a lightsignal (sometimes referred to as, “beam”) that is derived from (orassociated with) a local oscillator (LO) signal, one or more modulatorsfor modulating a phase and/or a frequency of the light signal usingContinuous Wave (CW) modulation or quasi-CW modulation, and an amplifierfor amplifying the modulated signal before sending the signal to optics(e.g., an oscillatory scanner, a unidirectional scanner, a Risley prism,a circulator optic, and/or a beam collimator, etc.).

The optics are configured to steer the amplified signal that it receivesfrom the Tx path into an environment within a given field of view towardan object, receive a returned signal reflected back from the object, andprovide the returned signal to the receive (Rx) path.

The Rx path may include a mixer (e.g., 50/50) for mixing the LO signalwith the returned signal to generate a down-converted signal, and atransimpedance (TIA) amplifier for amplifying the down-converted signal.The Rx path provides the down-converted signal (now amplified) to one ormore processors for determining a distance to the object and/ormeasuring the velocity of the object.

Operating an autonomous vehicle poses significant challenges for theconventional LIDAR system. First, the LIDAR system should be able todetect objects (e.g., street signs, people, cars, trucks, etc.) at shortdistances (e.g., less than 150 meters) and long distances (e.g., 300meters and beyond). Detecting objects at long distances, however, is notan easy feat for the conventional LIDAR system. Namely, the amplifiersof the conventional LIDAR system do not have enough power to amplify thetransmitted light signal enough for it to reach a long-distance object.Second, the beam scanning techniques used by conventional LIDAR systemsoften produce long measurement times, which in turn, require for theLIDAR system to meet a tighter and difficult speckle processingrequirements.

Accordingly, the present disclosure is directed to systems and methodsfor pulsed-wave LIDAR to support the operation of a vehicle.

In general, as described in the below passages, an implementation of apulsed-wave LIDAR system may be achieved by varying a gain configurationon an EDFA across a plurality of gain configurations of the EDFA. Forexample, the LIDAR system may include a laser source configured toprovide an optical signal; an erbium doped fiber amplifier (EDFA) thathas a plurality of gain configurations, where the EDFA is configured toreceive the optical signal, and amplify the optical signal based on again configuration of the plurality of gain configurations; and one ormore processors (e.g., autonomous vehicle control system 120, computingsystem 172, etc.) that are configured to adjust the gain configurationof the EDFA across at least a subset of the plurality of gainconfigurations to cause the EDFA to generate an amplified signalcorresponding to a pulse envelope signal.

Another implementation of a pulsed-wave LIDAR system may be achieved bytoggling an optical switch. For example, the pulsed-wave LIDAR systemmay include a laser source configured to provide an optical signal; anoptical switch having a first terminal, a second terminal, and a switchmode, where the optical switch is configured to receive the opticalsignal at the first terminal; and either allow a transmission of theoptical signal from the first terminal to the second terminal if theswitch mode is configured in a first mode, or block the transmission ofthe optical signal to the second terminal if the switch mode isconfigured in a second mode; and one or more processors configured totoggle the optical switch mode between the first mode and the secondmode to cause the optical switch to generate a pulse envelope signal.

Another implementation of a pulsed-wave LIDAR system may be achieved bydetecting a relative phase difference between two optical signals. Forexample, the pulse-wave LIDAR system may include a laser sourceconfigured to provide an optical signal; a pulse envelope generator(e.g., Mach-Zehnder modulator) configured to generate a pulse envelopesignal based on a relative phase difference between a first opticalsignal associated with the optical signal and a second optical signalassociated with the optical signal; and an EDFA configured to amplifythe pulse envelope signal and send the pulse envelope signal into freespace via one or more optical elements.

Another implementation of a pulsed-wave LIDAR system may be achieved bymodulating a light signal using an electrical field. For example, thepulse-wave LIDAR system may include a laser source configured to providean optical signal; a pulse envelope generator (e.g., electro-absorptionmodulator (EAM)) configured to generate a pulse envelope signal bymodulating the light signal using an electric field; and an EDFAconfigured to amplify the pulse envelope signal and send the amplifiedpulse envelope signal into free space via one or more optical elements.

Another implementation of a pulsed-wave LIDAR system may be achieved byvarying a gain configuration on a semiconductor optical amplifier (SOA)across a plurality of gain configurations of the SOA. For example, thepulse-wave LIDAR system may include a laser source configured to providean optical signal; an SOA having a plurality of gain configurations,where the SOA is configured to receive the optical signal, and amplifythe optical signal based on a gain configuration of the plurality ofgain configurations; and one or more processors configured to adjust thegain configuration of the SOA across at least a subset of the pluralityof gain configurations to cause the SOA to generate an amplified signalcorresponding to a pulse envelope signal.

The pulsed-wave LIDAR systems in the aforementioned implementations areable to achieve object recognition at a wide range of distances (e.g.,short and long) that are required for autonomous vehicle applications,and without having to produce more amplifier power than that capable bythe amplifiers in the conventional LIDAR system. Furthermore, thepulsed-wave LIDAR system relaxes the speckle processing requirements.

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present disclosure. It will be apparent, however,to one skilled in the art that the present disclosure may be practicedwithout these specific details. In other instances, well-knownstructures and devices are shown in block diagram form in order to avoidunnecessarily obscuring the present disclosure.

1. System Environment for Autonomous Vehicles

FIG. 1A is a block diagram illustrating an example of a systemenvironment for autonomous vehicles according to some implementations.

Referring to FIG. 1A, an example autonomous vehicle 100 within which thevarious techniques disclosed herein may be implemented. The vehicle 100,for example, may include a powertrain 102 including a prime mover 104powered by an energy source 106 and capable of providing power to adrivetrain 108, as well as a control system 110 including a directioncontrol 112, a powertrain control 114, and a brake control 116. Thevehicle 100 may be implemented as any number of different types ofvehicles, including vehicles capable of transporting people and/orcargo, and capable of traveling in various environments, and it will beappreciated that the aforementioned components 102-116 can vary widelybased upon the type of vehicle within which these components areutilized.

For simplicity, the implementations discussed hereinafter will focus ona wheeled land vehicle such as a car, van, truck, bus, etc. In suchimplementations, the prime mover 104 may include one or more electricmotors and/or an internal combustion engine (among others). The energysource may include, for example, a fuel system (e.g., providinggasoline, diesel, hydrogen, etc.), a battery system, solar panels orother renewable energy source, and/or a fuel cell system. The drivetrain108 can include wheels and/or tires along with a transmission and/or anyother mechanical drive components to convert the output of the primemover 104 into vehicular motion, as well as one or more brakesconfigured to controllably stop or slow the vehicle 100 and direction orsteering components suitable for controlling the trajectory of thevehicle 100 (e.g., a rack and pinion steering linkage enabling one ormore wheels of the vehicle 100 to pivot about a generally vertical axisto vary an angle of the rotational planes of the wheels relative to thelongitudinal axis of the vehicle). In some implementations, combinationsof powertrains and energy sources may be used (e.g., in the case ofelectric/gas hybrid vehicles), and in some instances multiple electricmotors (e.g., dedicated to individual wheels or axles) may be used as aprime mover.

The direction control 112 may include one or more actuators and/orsensors for controlling and receiving feedback from the direction orsteering components to enable the vehicle 100 to follow a desiredtrajectory. The powertrain control 114 may be configured to control theoutput of the powertrain 102, e.g., to control the output power of theprime mover 104, to control a gear of a transmission in the drivetrain108, etc., thereby controlling a speed and/or direction of the vehicle100. The brake control 116 may be configured to control one or morebrakes that slow or stop vehicle 100, e.g., disk or drum brakes coupledto the wheels of the vehicle.

Other vehicle types, including but not limited to off-road vehicles,all-terrain or tracked vehicles, construction equipment etc., willnecessarily utilize different powertrains, drivetrains, energy sources,direction controls, powertrain controls and brake controls. Moreover, insome implementations, some of the components can be combined, e.g.,where directional control of a vehicle is primarily handled by varyingan output of one or more prime movers. Therefore, implementationsdisclosed herein are not limited to the particular application of theherein-described techniques in an autonomous wheeled land vehicle.

Various levels of autonomous control over the vehicle 100 can beimplemented in a vehicle control system 120, which may include one ormore processors 122 and one or more memories 124, with each processor122 configured to execute program code instructions 126 stored in amemory 124. The processors(s) can include, for example, graphicsprocessing unit(s) (“GPU(s)”)) and/or central processing unit(s)(“CPU(s)”).

Sensors 130 may include various sensors suitable for collectinginformation from a vehicle's surrounding environment for use incontrolling the operation of the vehicle. For example, sensors 130 caninclude radar sensor 134, LIDAR (Light Detection and Ranging) sensor136, a 3D positioning sensors 138, e.g., any of an accelerometer, agyroscope, a magnetometer, or a satellite navigation system such as GPS(Global Positioning System), GLONASS (Globalnaya NavigazionnayaSputnikovaya Sistema, or Global Navigation Satellite System), BeiDouNavigation Satellite System (BDS), Galileo, Compass, etc. The 3Dpositioning sensors 138 can be used to determine the location of thevehicle on the Earth using satellite signals. The sensors 130 caninclude a camera 140 and/or an IMU (inertial measurement unit) 142. Thecamera 140 can be a monographic or stereographic camera and can recordstill and/or video images. The IMU 142 can include multiple gyroscopesand accelerometers capable of detecting linear and rotational motion ofthe vehicle in three directions. One or more encoders (not illustrated),such as wheel encoders may be used to monitor the rotation of one ormore wheels of vehicle 100. Each sensor 130 can output sensor data atvarious data rates, which may be different than the data rates of othersensors 130.

The outputs of sensors 130 may be provided to a set of controlsubsystems 150, including, a localization subsystem 152, a planningsubsystem 156, a perception subsystem 154, and a control subsystem 158.The localization subsystem 152 can perform functions such as preciselydetermining the location and orientation (also sometimes referred to as“pose”) of the vehicle 100 within its surrounding environment, andgenerally within some frame of reference. The location of an autonomousvehicle can be compared with the location of an additional vehicle inthe same environment as part of generating labeled autonomous vehicledata. The perception subsystem 154 can perform functions such asdetecting, tracking, determining, and/or identifying objects within theenvironment surrounding vehicle 100. A machine learning model inaccordance with some implementations can be utilized in trackingobjects. The planning subsystem 156 can perform functions such asplanning a trajectory for vehicle 100 over some timeframe given adesired destination as well as the static and moving objects within theenvironment. A machine learning model in accordance with someimplementations can be utilized in planning a vehicle trajectory. Thecontrol subsystem 158 can perform functions such as generating suitablecontrol signals for controlling the various controls in the vehiclecontrol system 120 in order to implement the planned trajectory of thevehicle 100. A machine learning model can be utilized to generate one ormore signals to control an autonomous vehicle to implement the plannedtrajectory.

It will be appreciated that the collection of components illustrated inFIG. 1A for the vehicle control system 120 is merely exemplary innature. Individual sensors may be omitted in some implementations.Additionally or alternatively, in some implementations, multiple sensorsof types illustrated in FIG. 1A may be used for redundancy and/or tocover different regions around a vehicle, and other types of sensors maybe used. Likewise, different types and/or combinations of controlsubsystems may be used in other implementations. Further, whilesubsystems 152-158 are illustrated as being separate from processor 122and memory 124, it will be appreciated that in some implementations,some or all of the functionality of a subsystem 152-158 may beimplemented with program code instructions 126 resident in one or morememories 124 and executed by one or more processors 122, and that thesesubsystems 152-158 may in some instances be implemented using the sameprocessor(s) and/or memory. Subsystems may be implemented at least inpart using various dedicated circuit logic, various processors, variousfield programmable gate arrays (“FPGA”), various application-specificintegrated circuits (“ASIC”), various real time controllers, and thelike, as noted above, multiple subsystems may utilize circuitry,processors, sensors, and/or other components. Further, the variouscomponents in the vehicle control system 120 may be networked in variousmanners.

In some implementations, the vehicle 100 may also include a secondaryvehicle control system (not illustrated), which may be used as aredundant or backup control system for the vehicle 100. In someimplementations, the secondary vehicle control system may be capable offully operating the autonomous vehicle 100 in the event of an adverseevent in the vehicle control system 120, while in other implementations,the secondary vehicle control system may only have limitedfunctionality, e.g., to perform a controlled stop of the vehicle 100 inresponse to an adverse event detected in the primary vehicle controlsystem 120. In still other implementations, the secondary vehiclecontrol system may be omitted.

In general, an innumerable number of different architectures, includingvarious combinations of software, hardware, circuit logic, sensors,networks, etc. may be used to implement the various componentsillustrated in FIG. 1A. Each processor may be implemented, for example,as a microprocessor and each memory may represent the random accessmemory (“RAM”) devices comprising a main storage, as well as anysupplemental levels of memory, e.g., cache memories, non-volatile orbackup memories (e.g., programmable or flash memories), read-onlymemories, etc. In addition, each memory may be considered to includememory storage physically located elsewhere in the vehicle 100, e.g.,any cache memory in a processor, as well as any storage capacity used asa virtual memory, e.g., as stored on a mass storage device or anothercomputer controller. One or more processors illustrated in FIG. 1A, orentirely separate processors, may be used to implement additionalfunctionality in the vehicle 100 outside of the purposes of autonomouscontrol, e.g., to control entertainment systems, to operate doors,lights, convenience features, etc.

In addition, for additional storage, the vehicle 100 may include one ormore mass storage devices, e.g., a removable disk drive, a hard diskdrive, a direct access storage device (“DASD”), an optical drive (e.g.,a CD drive, a DVD drive, etc.), a solid state storage drive (“SSD”),network attached storage, a storage area network, and/or a tape drive,among others.

Furthermore, the vehicle 100 may include a user interface 164 to enablevehicle 100 to receive a number of inputs from and generate outputs fora user or operator, e.g., one or more displays, touchscreens, voiceand/or gesture interfaces, buttons and other tactile controls, etc.Otherwise, user input may be received via another computer or electronicdevice, e.g., via an app on a mobile device or via a web interface.

Moreover, the vehicle 100 may include one or more network interfaces,e.g., network interface 162, suitable for communicating with one or morenetworks 170 (e.g., a Local Area Network (“LAN”), a wide area network(“WAN”), a wireless network, and/or the Internet, among others) topermit the communication of information with other computers andelectronic device, including, for example, a central service, such as acloud service, from which the vehicle 100 receives environmental andother data for use in autonomous control thereof. Data collected by theone or more sensors 130 can be uploaded to a computing system 172 viathe network 170 for additional processing. In some implementations, atime stamp can be added to each instance of vehicle data prior touploading.

Each processor illustrated in FIG. 1A, as well as various additionalcontrollers and subsystems disclosed herein, generally operates underthe control of an operating system and executes or otherwise relies uponvarious computer software applications, components, programs, objects,modules, data structures, etc., as will be described in greater detailbelow. Moreover, various applications, components, programs, objects,modules, etc. may also execute on one or more processors in anothercomputer coupled to vehicle 100 via network 170, e.g., in a distributed,cloud-based, or client-server computing environment, whereby theprocessing required to implement the functions of a computer program maybe allocated to multiple computers and/or services over a network.

In general, the routines executed to implement the variousimplementations described herein, whether implemented as part of anoperating system or a specific application, component, program, object,module or sequence of instructions, or even a subset thereof, will bereferred to herein as “program code”. Program code can include one ormore instructions that are resident at various times in various memoryand storage devices, and that, when read and executed by one or moreprocessors, perform the steps necessary to execute steps or elementsembodying the various aspects of the present disclosure. Moreover, whileimplementations have and hereinafter will be described in the context offully functioning computers and systems, it will be appreciated that thevarious implementations described herein are capable of beingdistributed as a program product in a variety of forms, and thatimplementations can be implemented regardless of the particular type ofcomputer readable media used to actually carry out the distribution.

Examples of computer readable media include tangible, non-transitorymedia such as volatile and non-volatile memory devices, floppy and otherremovable disks, solid state drives, hard disk drives, magnetic tape,and optical disks (e.g., CD-ROMs, DVDs, etc.) among others.

In addition, various program code described hereinafter may beidentified based upon the application within which it is implemented ina specific implementation. However, it should be appreciated that anyparticular program nomenclature that follows is used merely forconvenience, and thus the present disclosure should not be limited touse solely in any specific application identified and/or implied by suchnomenclature. Furthermore, given the typically endless number of mannersin which computer programs may be organized into routines, procedures,methods, modules, objects, and the like, as well as the various mannersin which program functionality may be allocated among various softwarelayers that are resident within a typical computer (e.g., operatingsystems, libraries, API's, applications, applets, etc.), it should beappreciated that the present disclosure is not limited to the specificorganization and allocation of program functionality described herein.

The environment illustrated in FIG. 1A is not intended to limitimplementations disclosed herein. Indeed, other alternative hardwareand/or software environments may be used without departing from thescope of implementations disclosed herein.

2. FM LIDAR for Automotive Applications

A truck can include a LIDAR system (e.g., vehicle control system 120 inFIG. 1A, LIDAR system 301A in FIG. 3A, LIDAR system 301B in FIG. 3B,LIDAR system 401A in FIG. 4A, LIDAR system 401B in FIG. 4B, LIDAR system501 in FIG. 5 , LIDAR system 601 in FIG. 6 , LIDAR system 701 in FIG. 7, LIDAR system 801 in FIG. 8 , etc.). In some implementations, the LIDARsystem can use frequency modulation to encode an optical signal andscatter the encoded optical signal into free-space using optics. Bydetecting the frequency differences between the encoded optical signaland a returned signal reflected back from an object, the frequencymodulated (FM) LIDAR system can determine the location of the objectand/or precisely measure the velocity of the object using the Dopplereffect. In some implementations, an FM LIDAR system may use a continuouswave (referred to as, “FMCW LIDAR”) or a quasi-continuous wave (referredto as, “FMQW LIDAR”). In some implementations, the LIDAR system can usephase modulation (PM) to encode an optical signal and scatters theencoded optical signal into free-space using optics.

An FM or phase-modulated (PM) LIDAR system may provide substantialadvantages over conventional LIDAR systems with respect to automotiveand/or commercial trucking applications. To begin, in some instances, anobject (e.g., a pedestrian wearing dark clothing) may have a lowreflectivity, in that it only reflects back to the sensors (e.g.,sensors 130 in FIG. 1A) of the FM or PM LIDAR system a low amount (e.g.,10% or less) of the light that hit the object. In other instances, anobject (e.g., a shiny road sign) may have a high reflectivity (e.g.,above 10%), in that it reflects back to the sensors of the FM LIDARsystem a high amount of the light that hit the object.

Regardless of the object's reflectivity, an FM LIDAR system may be ableto detect (e.g., classify, recognize, discover, etc.) the object atgreater distances (e.g., 2×) than a conventional LIDAR system. Forexample, an FM LIDAR system may detect a low reflectivity object beyond300 meters, and a high reflectivity object beyond 400 meters.

To achieve such improvements in detection capability, the FM LIDARsystem may use sensors (e.g., sensors 130 in FIG. 1A). In someimplementations, these sensors can be single photon sensitive, meaningthat they can detect the smallest amount of light possible. While an FMLIDAR system may, in some applications, use infrared wavelengths (e.g.,950 nm, 1550 nm, etc.), it is not limited to the infrared wavelengthrange (e.g., near infrared: 800 nm-1500 nm; middle infrared: 1500nm-5600 nm; and far infrared: 5600 nm-1,000,000 nm). By operating the FMor PM LIDAR system in infrared wavelengths, the FM or PM LIDAR systemcan broadcast stronger light pulses or light beams while meeting eyesafety standards. Conventional LIDAR systems are often not single photonsensitive and/or only operate in near infrared wavelengths, requiringthem to limit their light output (and distance detection capability) foreye safety reasons.

Thus, by detecting an object at greater distances, an FM LIDAR systemmay have more time to react to unexpected obstacles. Indeed, even a fewmilliseconds of extra time could improve safety and comfort, especiallywith heavy vehicles (e.g., commercial trucking vehicles) that aredriving at highway speeds.

Another advantage of an FM LIDAR system is that it provides accuratevelocity for each data point instantaneously. In some implementations, avelocity measurement is accomplished using the Doppler effect whichshifts frequency of the light received from the object based at leastone of the velocity in the radial direction (e.g., the direction vectorbetween the object detected and the sensor) or the frequency of thelaser signal. For example, for velocities encountered in on-roadsituations where the velocity is less than 100 meters per second (m/s),this shift at a wavelength of 1550 nanometers (nm) amounts to thefrequency shift that is less than 130 megahertz (MHz). This frequencyshift is small such that it is difficult to detect directly in theoptical domain. However, by using coherent detection in FMCW, PMCW, orFMQW LIDAR systems, the signal can be converted to the RF domain suchthat the frequency shift can be calculated using various signalprocessing techniques. This enables the autonomous vehicle controlsystem to process incoming data faster.

Instantaneous velocity calculation also makes it easier for the FM LIDARsystem to determine distant or sparse data points as objects and/ortrack how those objects are moving over time. For example, an FM LIDARsensor (e.g., sensors 130 in FIG. 1A) may only receive a few returns(e.g., hits) on an object that is 300 m away, but if those return give avelocity value of interest (e.g., moving towards the vehicle at >70mph), then the FM LIDAR system and/or the autonomous vehicle controlsystem may determine respective weights to probabilities associated withthe objects.

Faster identification and/or tracking of the FM LIDAR system gives anautonomous vehicle control system more time to maneuver a vehicle. Abetter understanding of how fast objects are moving also allows theautonomous vehicle control system to plan a better reaction.

Another advantage of an FM LIDAR system is that it has less staticcompared to conventional LIDAR systems. That is, the conventional LIDARsystems that are designed to be more light-sensitive typically performpoorly in bright sunlight. These systems also tend to suffer fromcrosstalk (e.g., when sensors get confused by each other's light pulsesor light beams) and from self-interference (e.g., when a sensor getsconfused by its own previous light pulse or light beam). To overcomethese disadvantages, vehicles using the conventional LIDAR systems oftenneed extra hardware, complex software, and/or more computational powerto manage this “noise.”

In contrast, FM LIDAR systems do not suffer from these types of issuesbecause each sensor is specially designed to respond only to its ownlight characteristics (e.g., light beams, light waves, light pulses). Ifthe returning light does not match the timing, frequency, and/orwavelength of what was originally transmitted, then the FM sensor canfilter (e.g., remove, ignore, etc.) out that data point. As such, FMLIDAR systems produce (e.g., generates, derives, etc.) more accuratedata with less hardware or software requirements, enabling safer andsmoother driving.

Lastly, an FM LIDAR system is easier to scale than conventional LIDARsystems. As more self-driving vehicles (e.g., cars, commercial trucks,etc.) show up on the road, those powered by an FM LIDAR system likelywill not have to contend with interference issues from sensor crosstalk.Furthermore, an FM LIDAR system uses less optical peak power thanconventional LIDAR sensors. As such, some or all of the opticalcomponents for an FM LIDAR can be produced on a single chip, whichproduces its own benefits, as discussed herein.

2.1 Commercial Trucking

FIG. 1B is a block diagram illustrating an example of a systemenvironment for autonomous commercial trucking vehicles, according tosome implementations. The environment 100B includes a commercial truck102B for hauling cargo 106B. In some implementations, the commercialtruck 102B may include vehicles configured to long-haul freighttransport, regional freight transport, intermodal freight transport(i.e., in which a road-based vehicle is used as one of multiple modes oftransportation to move freight), and/or any other road-based freighttransport applications. In some implementations, the commercial truck102B may be a flatbed truck, a refrigerated truck (e.g., a reefertruck), a vented van (e.g., dry van), a moving truck, etc. In someimplementations, the cargo 106B may be goods and/or produce. In someimplementations, the commercial truck 102B may include a trailer tocarry the cargo 106B, such as a flatbed trailer, a lowboy trailer, astep deck trailer, an extendable flatbed trailer, a sidekit trailer,etc.

The environment 100B includes an object 110B (shown in FIG. 1B asanother vehicle) that is within a distance range that is equal to orless than 30 meters from the truck.

The commercial truck 102B may include a LIDAR system 104B (e.g., an FMLIDAR system, vehicle control system 120 in FIG. 1A, LIDAR system 201 inFIG. 2 , etc.) for determining a distance to the object 110B and/ormeasuring the velocity of the object 110B. Although FIG. 1B shows thatone LIDAR system 104B is mounted on the front of the commercial truck102B, the number of LIDAR system and the mounting area of the LIDARsystem on the commercial truck are not limited to a particular number ora particular area. The commercial truck 102B may include any number ofLIDAR systems 104B (or components thereof, such as sensors, modulators,coherent signal generators, etc.) that are mounted onto any area (e.g.,front, back, side, top, bottom, underneath, and/or bottom) of thecommercial truck 102B to facilitate the detection of an object in anyfree-space relative to the commercial truck 102B.

As shown, the LIDAR system 104B in environment 100B may be configured todetect an object (e.g., another vehicle, a bicycle, a tree, streetsigns, potholes, etc.) at short distances (e.g., 30 meters or less) fromthe commercial truck 102B.

FIG. 1C is a block diagram illustrating an example of a systemenvironment for autonomous commercial trucking vehicles, according tosome implementations. The environment 100C includes the same components(e.g., commercial truck 102B, cargo 106B, LIDAR system 104B, etc.) thatare included in environment 100B.

The environment 100C includes an object 110C (shown in FIG. 1C asanother vehicle) that is within a distance range that is (i) more than30 meters and (ii) equal to or less than 150 meters from the commercialtruck 102B. As shown, the LIDAR system 104B in environment 100C may beconfigured to detect an object (e.g., another vehicle, a bicycle, atree, street signs, potholes, etc.) at a distance (e.g., 100 meters)from the commercial truck 102B.

FIG. 1D is a block diagram illustrating an example of a systemenvironment for autonomous commercial trucking vehicles, according tosome implementations. The environment 100D includes the same components(e.g., commercial truck 102B, cargo 106B, LIDAR system 104B, etc.) thatare included in environment 100B.

The environment 100D includes an object 110D (shown in FIG. 1D asanother vehicle) that is within a distance range that is more than 150meters from the commercial truck 102B. As shown, the LIDAR system 104Bin environment 100D may be configured to detect an object (e.g., anothervehicle, a bicycle, a tree, street signs, potholes, etc.) at a distance(e.g., 300 meters) from the commercial truck 102B.

In commercial trucking applications, it is important to effectivelydetect objects at all ranges due to the increased weight and,accordingly, longer stopping distance required for such vehicles. FMLIDAR systems (e.g., FMCW and/or FMQW systems) or PM LIDAR systems arewell-suited for commercial trucking applications due to the advantagesdescribed above. As a result, commercial trucks equipped with suchsystems may have an enhanced ability to safely move both people andgoods across short or long distances, improving the safety of not onlythe commercial truck but of the surrounding vehicles as well. In variousimplementations, such FM or PM LIDAR systems can be used insemi-autonomous applications, in which the commercial truck has a driverand some functions of the commercial truck are autonomously operatedusing the FM or PM LIDAR system, or fully autonomous applications, inwhich the commercial truck is operated entirely by the FM or LIDARsystem, alone or in combination with other vehicle systems.

3. CW Operation, Quasi-CW Operation, and Pulsed-Wave Operation

In a LIDAR system that uses CW modulation (sometimes referred to as, “CWoperation”), the modulator modulates the laser light continuously. Forexample, if a modulation cycle is 10 microseconds, an input signal ismodulated throughout the whole 10 microseconds.

In a LIDAR system that uses quasi-CW modulation (sometimes referred toas, “quasi-CW operation”), the modulator modulates the laser light tohave both an active portion and an inactive portion. For example, for a10 microsecond cycle, the modulator modulates the laser light only for 2microseconds (sometimes referred to as, “the active portion”), but doesnot modulate the laser light for 8 microseconds (sometimes referred toas, “the inactive portion”). Since the light signal does not have to bein the on-state (e.g., enabled, powered, transmitting, etc.) all thetime, the LIDAR system may be able to reduce power consumption for theportion of time (e.g., 8 microseconds) where the modulator does not haveto provide a continuous signal. Furthermore, if the energy in theoff-state (e.g., disabled, powered-down, etc.) can be expended duringthe actual measurement time, then there may be a boost tosignal-to-noise ratio (SNR) and/or a reduction in signal processingrequirements to coherently integrate all the energy in the longer timescale.

In a LIDAR system that uses pulsed-wave modulation (sometimes referredto as, “pulsed-wave operation”), the modulator modulates the laser lightto have both an active portion and an inactive portion. One or moregates then seed the laser input to an optical amplifier via an opticalswitch, thereby taking advantage of the optical gain buildup thatresults in an instantaneous output power increase of 1/(optical dutycycle) and a reduction (e.g., by the duty cycle) in the processingrequirements, all while maintaining a constant signal power.

FIG. 2 is a time-based graph depicting the differences (e.g.,differences in amplitude, period, average power, duty cycle, etc.)between the waveforms produced by one or more LIDAR systems that use CWoperation, quasi-CW operation, and/or pulsed-wave operation. Thetime-based graph 200 includes waveform 202 a, waveform 202 b, andwaveform 202 c. A LIDAR system (e.g., LIDAR 136 in FIG. 1A) that uses CWoperation may construct a waveform 202 a (e.g., a continuous wave)having an amplitude of ‘h’ based on a plurality of Codes (e.g., Code 1,Code 2, Code 3, and Code 4). A LIDAR system (e.g., LIDAR 136 in FIG. 1A)that uses quasi-CW operation may construct a waveform 202 b (e.g., aquasi-CW) having a duty cycle equal (or substantially equal) to 50% andan amplitude that this equal to (or substantially equal to) twice (e.g.,2 h) the amplitude of waveform 202 a based on a plurality of Codes(e.g., Code 1 and Code 2). A LIDAR system (e.g., LIDAR 136 in FIG. 1A)that uses pulsed-wave operation may construct a waveform 202 c (e.g., apulsed-wave) having a duty cycle that is equal (or substantially equal)to 1/12 the duty cycle of waveform 202 a and an amplitude that thisequal (or substantially equal) to 12× (e.g., 12 h) the amplitude ofwaveform 202 a based on a plurality of Codes (e.g., Code 1 and Code 2).

4. Pulsed-Wave Operation Using an EDFA

FIG. 3A is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an EDFA for operating anautonomous vehicle, according to some implementations. The environment300A includes a LIDAR system 301A that includes a transmit (Tx) path anda receive (Rx) path. The Tx path may include one or more Tx input/outputports (not shown in FIG. 3A) and the Rx path may include one or more Rxinput/output ports (not shown in FIG. 3A).

The environment 300A includes one or more optics 310 (e.g., anoscillatory scanner, a unidirectional scanner, a Risley prism, acirculator optic, and/or a beam collimator, etc.) that are coupled tothe LIDAR system 301A. In some implementations, the one or more optics210 may be coupled to the Tx path via the one or more Tx input/outputports. In some implementations, the one or more optics 310 may becoupled to the Rx path via the one or more Rx input/output ports.

The environment 300A includes a vehicle control system 120 (e.g.,vehicle control system 120 in FIG. 1 ) that is coupled to the LIDARsystem 301. In some implementations, the vehicle control system 120 maybe coupled to the Rx path via the one or more Rx input/output ports.

The Tx path includes a laser source 302, an electro-optic modulator(EOM) 304A, and an erbium doped fiber amplifier (EDFA) 306. The Rx pathincludes a mixer 308, a detector 312, and a transimpedance (TIA) 212.Although FIG. 3A shows only a select number of components and only oneinput/output channel; the environment 300A may include any number ofcomponents and/or input/output channels (in any combination) that areinterconnected in any arrangement to facilitate combining multiplefunctions of a LIDAR system, to support the operation of a vehicle.

The laser source 302 is configured to generate a light signal that isderived from (or associated with) a local oscillator (LO) signal. Insome implementations, the light signal may have an operating wavelengththat is equal to or substantially equal to 1550 nanometers. In someimplementations, the light signal may have an operating wavelength thatis between 1400 nanometers and 1600 nanometers.

The laser source 302 is configured to provide the light signal to theEOM 304A, which is configured to modulate a phase and/or a frequency ofthe light signal based on a code signal (e.g., “00011010”) to generate amodulated light signal. The EOM 304A is configured to send the modulatedlight signal to the EDFA 306. The EDFA 306 is associated with aplurality of gain configurations, each that determine the level at whichthe EDFA 306 should amplify (e.g., boost) an input signal. In someimplementations, the EDFA 306 may be configured in a constant currentmode.

One or more processors (e.g., autonomous vehicle control system 120,computing system 172, etc.) are configured to vary (e.g., change,adjust, modify, etc.) a gain configuration of the EDFA 306 to cause theEDFA 306 to generate a pulsed envelope signal by amplifying themodulated light signal. The one or more processors, in someimplementations, may vary the gain configuration of the EDFA 306 acrossone or more gain configurations (e.g., a subset, all) of the pluralityof gain configurations in a random, periodic (e.g., at any point between0.1 milliseconds to 5 milliseconds, etc.), or continuous manner. TheEDFA 306 is configured to send the pulsed envelope signal to the optics310.

The optics 310 are configured to steer the amplified light signal thatit receives from the Tx path into free space within a given field ofview toward an object 318, receive a returned signal reflected back fromthe object 318 via a receiver (not shown in FIG. 3A), and provide thereturned signal to the mixer 308 of the Rx path.

The laser source 302, in some implementations, may be configured toprovide an unmodulated LO signal (not shown in FIG. 3A) to the mixer 308of the Rx path. The EOM 304, in some implementations, may be configuredto provide a modulated LO signal (not shown in FIG. 3A) to the mixer 308of the Rx path.

The mixer 308 is configured to mix (e.g., combine, multiply, etc.) theLO signal (modulated or unmodulated) with the returned signal togenerate a down-converted signal and send the down-converted signal tothe detector 312. In some arrangements, the mixer 308 is configured tosend the LO signal (modulated or unmodulated) to the detector 312.

The detector 312 is configured to generate an electrical signal based onthe down-converted signal and send the electrical signal to the TIA 314.In some arrangements, the detector 312 is configured to generate anelectrical signal based on the down-converted signal and the modulatedlight signal.

The TIA 314 is configured to amplify the electrical signal and send theamplified electrical signal to the vehicle control system 120.

The vehicle control system 120 is configured to determine a distance tothe object 318 and/or measures the velocity of the object 318 based onthe one or more electrical signals that it receives from the TIA.

FIG. 3B is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an EDFA and directlymodulating a laser source for operating an autonomous vehicle, accordingto some implementations. Other than the removal of the electro-opticmodulator (EOM) 304A, the environment 300B in FIG. 3B includes the samecomponents (and at least their same functionality) as the environment300A in FIG. 3A.

The laser source 302 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 302 isalso configured to modulate a phase and/or a frequency of the lightsignal based on a code signal (e.g., “00011010”) to generate a modulatedlight signal. The laser source 302 is configured to send the modulatedlight signal to the EDFA 306. The laser source 302, in someimplementations, may be configured to provide an unmodulated ormodulated LO signal (not shown in FIG. 3B) to the mixer 308 of the Rxpath.

One or more processors (e.g., autonomous vehicle control system 120,computing system 172, etc.) are configured to vary (e.g., change,adjust, modify, etc.) a gain configuration of the EDFA 306 to cause theEDFA 306 to generate a pulsed envelope signal by amplifying themodulated light signal. The one or more processors, in someimplementations, may vary the gain configuration of the EDFA 306 acrossone or more gain configurations (e.g., a subset, all) of the pluralityof gain configurations in a random, periodic (e.g., at any point between0.1 milliseconds to 5 milliseconds, etc.), or continuous manner. TheEDFA 306 is configured to send the pulsed envelope signal to the optics310

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

An EDFA (e.g., EDFA 306 in FIG. 3A and/or FIG. 3B), in someimplementations, may have a constant pumping rate of the gain, which inthe absence of light on the input may cause the gain to increase overtime, building up potential energy for optical energy release when anoptical pulse is input to the EDFA. This energy storage mechanism of theEDFA makes it simple to concentrate the output optical energy into apulse and achieve relatively similar average power (e.g., averaged overmany pulse cycles) to if the input and output of the EDFA werecontinuous or quasi-continuous.

FIG. 3C illustrates an example waveform of the optical intensity beforean EDFA, where the EDFA has a constant pumping rate of gain, accordingto some implementations. FIG. 3D illustrates an example waveform of theoptical intensity after an EDFA, where the EDFA has a constant pumpingrate of gain, according to some implementations. However, in someimplementations, the power in the pulse in both instances (e.g., beforeand after) would be increased by the inverse of the duty cycle.

5. Pulsed-Wave Operation Using an Optical Switch

FIG. 4A is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an optical switch foroperating an autonomous vehicle, according to some implementations. Theenvironment 400A includes a LIDAR system 401A that includes a transmit(Tx) path and a receive (Rx) path. The Tx path may include one or moreTx input/output ports (not shown in FIG. 4A) and the Rx path may includeone or more Rx input/output ports (not shown in FIG. 4A).

The environment 400A includes one or more optics 310 that are coupled tothe LIDAR system 401A. In some implementations, the one or more optics310 may be coupled to the Tx path via the one or more Tx input/outputports. In some implementations, the one or more optics 310 may becoupled to the Rx path via the one or more Rx input/output ports.

The environment 400A includes a vehicle control system 120 (e.g.,vehicle control system 120 in FIG. 1 ) that is coupled to the LIDARsystem 401. In some implementations, the vehicle control system 120 maybe coupled to the Rx path via the one or more Rx input/output ports.

The Tx path includes a laser source 402, an electro-optic modulator(EOM) 404A, an optical switch 405, and an erbium doped fiber amplifier(EDFA) 406. The Rx path includes a mixer 308, a detector 312, and atransimpedance (TIA) 312. Although FIG. 4A shows only a select number ofcomponents and only one input/output channel; the environment 400A mayinclude any number of components and/or input/output channels (in anycombination) that are interconnected in any arrangement to facilitatecombining multiple functions of a LIDAR system, to support the operationof a vehicle.

The laser source 402 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 402 isconfigured to provide the light signal to the EOM 404A. The laser source402, in some implementations, may be configured to provide anunmodulated LO signal (not shown in FIG. 3A) to the mixer 308 of the Rxpath.

The EOM 404A is configured to modulate a phase and/or a frequency of thelight signal based on a code signal (e.g., “00011010”) to generate amodulated light signal. The EOM 404A is configured to send the modulatedlight signal to the optical switch 405. The EOM 404A, in someimplementations, may be configured to modulate an LO signal (not shownin FIG. 4A) and provide the modulated LO signal to the mixer 308 of theRx path.

One or more processors (e.g., autonomous vehicle control system 120,computing system 172, etc.) are configured to toggle (e.g., activate,deactivate, enable, disable, move, flip, adjust, configure, etc.) theoptical switch 405 between an enabled state (e.g., allowing a lightsignal to pass between an input and an output of the switch) anddisabled state (e.g., preventing a light signal from passing between aninput and an output of the switch) to cause the optical switch 405 togenerate a pulsed envelope signal based on the modulated light signal.The one or more processors, in some implementations, may toggle theoptical switch 405 in a random, periodic (e.g., at any point between 0.1microseconds to 10 microseconds, etc.) or continuous manner. The opticalswitch 405 is configured to send the pulsed envelope signal to the EDFA406.

The EDFA 406 is configured to generate an amplified pulsed envelopesignal by amplifying the pulsed envelope signal and send the amplifiedpulsed envelope signal to the optics 310.

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

The waveform at node 411 (i.e., output of laser 402) that corresponds tothe optical signal may be represented by the following equation:

E ₄₁₁ =E ₀ *e ^(i(wt))  (1)

The waveform at node 413 (i.e., output of EOM 404) that corresponds tothe modulated optical signal may be represented by the followingequation:

E ₄₁₃ =E ₀ *e ^(i(wt+∅t))  (2)

where ∅(t)=π(code).

The waveform at node 415 (i.e., output of switch 405) that correspondsto the pulse envelope signal may be represented by the followingequation:

E ₄₁₅ 'E ₄₁₃⋅ψ(t)  (3)

where ψ={1, t=0: T 0, t=T: PRP}

FIG. 4B is a block diagram illustrating an example environment of aLIDAR system in pulsed-wave operation using an optical switch foroperating an autonomous vehicle, according to some implementations.Other than the removal of the electro-optic modulator (EOM) 404A, theenvironment 400B in FIG. 4B includes the same components (and at leasttheir same functionality) as the environment 400A in FIG. 4A.

The laser source 402 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 402 isalso configured to modulate a phase and/or a frequency of the lightsignal based on a code signal (e.g., “00011010”) to generate a modulatedlight signal. The laser source 402 is configured to send the modulatedlight signal to the optical switch 405. The laser source 402, in someimplementations, may be configured to provide an unmodulated ormodulated LO signal (not shown in FIG. 4B) to the mixer 308 of the Rxpath.

One or more processors (e.g., autonomous vehicle control system 120,computing system 172, etc.) are configured to toggle (e.g., activate,deactivate, enable, disable, move, flip, adjust, configure, etc.) theoptical switch 405 between an enabled state (e.g., allowing a lightsignal to pass between an input and an output of the switch) anddisabled state (e.g., preventing a light signal from passing between aninput and an output of the switch) to cause the optical switch 405 togenerate a pulsed envelope signal based on the modulated light signal.The one or more processors, in some implementations, may toggle theoptical switch 405 in a random, periodic (e.g., at any point between 0.1microseconds to 10 microseconds, etc.) or continuous manner. The opticalswitch 405 is configured to send the pulsed envelope signal to the EDFA406.

The EDFA 406 is configured to generate an amplified pulsed envelopesignal by amplifying the pulsed envelope signal and send the amplifiedpulsed envelope signal to the optics 310.

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

FIG. 4C is a flow chart that illustrates an example method forpulsed-wave LIDAR to support the operation of a vehicle, according to animplementation. Although steps are depicted in FIG. 4C as integral stepsin a particular order for purposes of illustration, in otherimplementations, one or more steps, or portions thereof, are performedin a different order, or overlapping in time, in series or in parallel,or are omitted, or one or more additional steps are added, or the methodis changed in some combination of ways. In some implementations, some orall operations of method 400C may be performed by one or more of thecomponents (e.g., LIDAR system 401, optics 310, autonomous vehiclecontrol system 120) depicted in environment 400A in FIG. 4A. In someimplementations, some or all operations of method 400C may be performedby one or more of the components (e.g., LIDAR system 401, optics 310,autonomous vehicle control system 120) depicted in environment 400B inFIG. 4B.

The method 400C includes the operation 402C of modulating an opticalsignal to generate a modulated optical signal. In some implementations,the method 400C includes the operation 404C of selecting a plurality ofpulses from the modulated optical signal to generate a pulsed envelopesignal. In some implementations, the method 400C includes the operation406C of transmitting the pulsed envelope signal via one or more opticalelements. In some implementations, the method 400C includes theoperation 408C of receiving a reflected signal responsive totransmitting the pulsed envelope signal. In some implementations, themethod 400C includes the operation 410C of determining a range to anobject based on an electrical signal associated with the reflectedsignal.

6. Pulsed-Wave Operation Using a Mach-Zehnder Modulator

FIG. 5 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using a Mach-Zehnder modulator foroperating an autonomous vehicle, according to some implementations. Theenvironment 500A includes a LIDAR system 501 that includes a transmit(Tx) path and a receive (Rx) path. The Tx path may include one or moreTx input/output ports (not shown in FIG. 5 ) and the Rx path may includeone or more Rx input/output ports (not shown in FIG. 5 ).

The environment 500A includes one or more optics 310 that are coupled tothe LIDAR system 501. In some implementations, the one or more optics310 may be coupled to the Tx path via the one or more Tx input/outputports. In some implementations, the one or more optics 310 may becoupled to the Rx path via the one or more Rx input/output ports.

The environment 500A includes a vehicle control system 120 (e.g.,vehicle control system 120 in FIG. 1 ) that is coupled to the LIDARsystem 501. In some implementations, the vehicle control system 120 maybe coupled to the Rx path via the one or more Rx input/output ports.

The Tx path includes a laser source 502, a Mach-Zehnder modulator 505,and an erbium doped fiber amplifier (EDFA) 506. The Rx path includes amixer 308, a detector 312, and a transimpedance (TIA) 312. Although FIG.5 shows only a select number of components and only one input/outputchannel, the environment 500A may include any number of componentsand/or input/output channels (in any combination) that areinterconnected in any arrangement to facilitate combining multiplefunctions of a LIDAR system, to support the operation of a vehicle.

The laser source 502 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 502 isconfigured to provide the light signal to the Mach-Zehnder modulator505. The laser source 502, in some implementations, may be configured toprovide an LO signal (not shown in FIG. 5 ) to the mixer 308 of the Rxpath.

The Mach-Zehnder modulator 505 is configured to convert the relativephase shift variations between two paths derived by splitting the lightsignal from the laser source 502 and modulating the two paths withelectro-optic modulation. The Mach-Zehnder modulator 505 is configuredto generate a pulse envelope signal based on the relative phasevariations. In some implementations, the Mach-Zehnder modulator 505modulates a phase and/or a frequency of the pulse envelope signal basedon a code signal (e.g., “00011010”) to generate a modulated pulseenvelope signal. The Mach-Zehnder modulator 505 is configured to sendthe pulse envelope signal (unmodulated or modulated) to the EDFA 506.The Mach-Zehnder modulator 505 may, in some implementations, modulate anLO signal and provide the modulated LO signal to the mixer 308 of the Rxpath. The Mach-Zehnder modulator 505 may, in some implementations, beused with pulse shaping to correct for output amplitude decay on asignal.

The EDFA 506 is configured to generate an amplified pulsed envelopesignal by amplifying the pulsed envelope signal and send the amplifiedpulsed envelope signal to the optics 310.

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

Referring back to FIG. 5 , one or more processors (e.g., autonomousvehicle control system 120, computing system 172, etc.) are configuredto toggle (e.g., activate, deactivate, enable, disable, move, flip,adjust, configure, etc.) the output of the MZ modulator 505 between anenabled state (e.g., allowing a light signal to pass between an inputand an output) and disabled state (e.g., preventing a light signal frompassing between an input and an output) such that the MZ modulator 505can generate a pulsed envelope signal in addition to the modulated lightsignal. The one or more processors, in some implementations, may togglethe output of the MZ modulator 505 in a random, periodic (e.g., at anypoint between 0.1 microseconds to 10 microseconds, etc.), or continuousmanner. The the MZ modulator 505 is configured to send the modulatedpulsed envelope signal to the EDFA 506.

In some implementations, the waveform at node 511 (i.e., output of laser502) that corresponds to the optical signal may be represented by thefollowing equation:

E ₅₁₁ =E ₀ *e ^(i(wt)).   (4)

In some implementations, the waveform at node 515 (i.e., output of MZmodulator 505) that corresponds to the modulated and pulsed opticalsignal may be represented by the following equation:

E ₅₁₅ =E ₀ *e ^(t(wt))*Code*ψ(t).  (5)

where=ψ={1,t=0: T 0, t=TL PRP}.

7. Pulsed-Wave Operation Using an EAM

FIG. 6 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using an electro-absorption modulator(EAM) for operating an autonomous vehicle, according to someimplementations. The environment 600 includes a LIDAR system 601 thatincludes a transmit (Tx) path and a receive (Rx) path. The Tx path mayinclude one or more Tx input/output ports (not shown in FIG. 6 ) and theRx path may include one or more Rx input/output ports (not shown in FIG.6 ).

The environment 600 includes one or more optics 310 that are coupled tothe LIDAR system 601. In some implementations, the one or more optics310 may be coupled to the Tx path via the one or more Tx input/outputports. In some implementations, the one or more optics 310 may becoupled to the Rx path via the one or more Rx input/output ports.

The environment 600 includes a vehicle control system 120 (e.g., vehiclecontrol system 120 in FIG. 1 ) that is coupled to the LIDAR system 601.In some implementations, the vehicle control system 120 may be coupledto the Rx path via the one or more Rx input/output ports.

The Tx path includes a laser source 602, an EAM 605, and an erbium dopedfiber amplifier (EDFA) 606. The Rx path includes a mixer 308, a detector312, and a transimpedance (TIA) 312. Although FIG. 6 shows only a selectnumber of components and only one input/output channel; the environment600 may include any number of components and/or input/output channels(in any combination) that are interconnected in any arrangement tofacilitate combining multiple functions of a LIDAR system, to supportthe operation of a vehicle.

The laser source 602 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 602 isconfigured to provide the light signal to the EAM 605. The laser source602, in some implementations, may be configured to provide an LO signal(not shown in FIG. 6 ) to the mixer 308 of the Rx path.

The EAM 605 is configured to modulate the amplitude (e.g., intensity) ofthe light signal via an electric voltage according to a code signal(e.g., “00011010”). That is, the EAM 605 is constructed from asemiconductor material that has an absorption coefficient. When one ormore processors (e.g., autonomous vehicle control system 120, computingsystem 172, etc.) apply an external electric field to the EAM 605, theabsorption coefficient changes resulting in a change in the bandgapenergy, which in turn, causes the EAM 605 to modulate the amplitude ofthe incoming light signal. By modulating the amplitude of the lightsignal, the EAM 605 is able to generate a pulse envelope signal. The EAM605 is configured to send the pulse envelope signal to the EDFA 606. TheEAM 605 may, in some implementations, modulate an LO signal and providethe modulated LO signal to the mixer 308 of the Rx path.

The EDFA 606 amplifies the pulse envelope signal to generate anamplified pulse envelope signal and sends the amplified pulsed envelopesignal to the optics 310.

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

8. Pulsed-Wave Operation Using an SOA

FIG. 7 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using a semiconductor optical amplifier(SOA) for operating an autonomous vehicle, according to someimplementations. The environment 700 includes a LIDAR system 701 thatincludes a transmit (Tx) path and a receive (Rx) path. The Tx path mayinclude one or more Tx input/output ports (not shown in FIG. 7 ) and theRx path may include one or more Rx input/output ports (not shown in FIG.7 ).

The environment 700 includes one or more optics 310 that are coupled tothe LIDAR system 701. In some implementations, the one or more optics310 may be coupled to the Tx path via the one or more Tx input/outputports. In some implementations, the one or more optics 310 may becoupled to the Rx path via the one or more Rx input/output ports.

The environment 700 includes a vehicle control system 120 (e.g., vehiclecontrol system 120 in FIG. 1 ) that is coupled to the LIDAR system 701.In some implementations, the vehicle control system 120 may be coupledto the Rx path via the one or more Rx input/output ports.

The Tx path includes a laser source 702, a modulator 705, asemiconductor optical amplifier (SOA) 706. The Rx path includes a mixer308, a detector 312, and a transimpedance (TIA) 312. Although FIG. 7shows only a select number of components and only one input/outputchannel; the environment 700 may include any number of components and/orinput/output channels (in any combination) that are interconnected inany arrangement to facilitate combining multiple functions of a LIDARsystem, to support the operation of a vehicle.

The laser source 702 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 702 isconfigured to provide the light signal to the modulator 705. The lasersource 702, in some implementations, may be configured to provide an LOsignal (not shown in FIG. 7 ) to the mixer 308 of the Rx path.

The modulator is configured to modulate a phase and/or a frequencyand/or intensity of the light signal based on a code signal (e.g.,“00011010”) to generate a modulated light signal. The modulator 705, insome implementations, may be an EOM (e.g., EOM 404 in FIG. 4A), an EAM(e.g., EAM 605 in FIG. 6 ), or a Mach-Zehnder modulator (e.g.,Mach-Zehnder modulator 505 in FIG. 5 ). The modulator 705 is configuredto send the modulated light signal to the SOA 706. The modulator 705may, in some implementations, modulate an LO signal and provide themodulated LO signal to the mixer 308 of the Rx path.

The SOA 706 may be associated with a plurality of gain configurations,each that determine the level at which the SOA 706 should amplify (e.g.,boost) an input signal.

One or more processors (e.g., autonomous vehicle control system 120,computing system 172, etc.) are configured to vary (e.g., change,adjust, modify, etc.) a gain configuration of the SOA 706 to cause theSOA 706 to generate a pulsed envelope signal by amplifying the modulatedlight signal. The one or more processors, in some implementations, mayvary the gain configuration of the SOA 706 across one or more gainconfigurations (e.g., a subset, all) of the plurality of gainconfigurations in a random, periodic (e.g., at any point between 0.1microseconds to 10 microseconds, etc.), or continuous manner. The SOA706 is configured to send the pulsed envelope signal to the optics 310.

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

FIG. 8 is a block diagram illustrating an example environment of a LIDARsystem in pulsed-wave operation using a semiconductor optical amplifier(SOA) and index modulation for operating an autonomous vehicle,according to some implementations. Other than the removal of themodulator 705, the environment 800B in FIG. 8 includes the samecomponents (and at least their same functionality) as the environment700 in FIG. 7 .

The laser source 802 is configured to generate a light signal that isderived from (or associated with) an LO signal. The laser source 802 isconfigured to send the modulated light signal to the SOA 806. The lasersource 802, in some implementations, may be configured to provide an LOsignal (not shown in FIG. 8 ) to the mixer 308 of the Rx path.

The SOA 806 is associated with a plurality of gain configurations, eachthat determine the level at which the SOA 806 should amplify (e.g.,boost) an input signal.

One or more processors (e.g., autonomous vehicle control system 120,computing system 172, etc.) are configured to vary (e.g., change,adjust, modify, etc.) a gain configuration of the SOA 806 to cause theSOA 806 to generate a pulsed envelope signal by amplifying the modulatedlight signal. The one or more processors, in some implementations, mayvary the gain configuration of the SOA 806 across one or more gainconfigurations (e.g., a subset, all) of the plurality of gainconfigurations in a random, periodic (e.g., at any point between 0.1microseconds to 10 microseconds, etc.), or continuous manner.

The SOA 806 is configured to modulate the light signal and/or the pulseenvelope signal using index modulation and based on a code signal (e.g.,“00011010”). The SOA 806 is configured to send the pulsed envelopesignal to the optics 310. The SOA 806 may, in some implementations,modulate an LO signal and provide the modulated LO signal to the mixer308 of the Rx path.

As discussed herein with respect to FIG. 3A, the optics 310 areconfigured to steer the light signal that it receives from the Tx pathinto free space within a given field of view toward an object 318,receive a returned signal reflected back from the object 318 via areceiver, and provide the returned signal to the Rx path. The Rx pathgenerates one or more electrical signals from the returned signal anddelivers the one or more electrical signals to the vehicle controlsystem 120, which is configured to determine a distance to the object318 and/or measures the velocity of the object 318 based on the one ormore electrical signals that it receives from the Rx path.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout the previous description that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. No claim element is to be construed as a means plus functionunless the element is expressly recited using the phrase “means for.”

It is understood that the specific order or hierarchy of blocks in theprocesses disclosed is an example of illustrative approaches. Based upondesign preferences, it is understood that the specific order orhierarchy of blocks in the processes may be rearranged while remainingwithin the scope of the previous description. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description of the disclosed implementations is provided toenable any person skilled in the art to make or use the disclosedsubject matter. Various modifications to these implementations will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other implementations without departingfrom the spirit or scope of the previous description. Thus, the previousdescription is not intended to be limited to the implementations shownherein but is to be accorded the widest scope consistent with theprinciples and novel features disclosed herein.

The various examples illustrated and described are provided merely asexamples to illustrate various features of the claims. However, featuresshown and described with respect to any given example are notnecessarily limited to the associated example and may be used orcombined with other examples that are shown and described. Further, theclaims are not intended to be limited by any one example.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the blocks of various examples must be performed in theorder presented. As will be appreciated by one of skill in the art theorder of blocks in the foregoing examples may be performed in any order.Words such as “thereafter,” “then,” “next,” etc. are not intended tolimit the order of the blocks; these words are simply used to guide thereader through the description of the methods. Further, any reference toclaim elements in the singular, for example, using the articles “a,”“an” or “the” is not to be construed as limiting the element to thesingular.

The various illustrative logical blocks, modules, circuits, andalgorithm blocks described in connection with the examples disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and blocks have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The hardware used to implement the various illustrative logics, logicalblocks, modules, and circuits described in connection with the examplesdisclosed herein may be implemented or performed with a general purposeprocessor, a DSP, an ASIC, an FPGA or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but, in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. Alternatively, some blocks or methods may be performed bycircuitry that is specific to a given function.

In some exemplary examples, the functions described may be implementedin hardware, software, firmware, or any combination thereof. Ifimplemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable storagemedium or non-transitory processor-readable storage medium. The blocksof a method or algorithm disclosed herein may be embodied in aprocessor-executable software module which may reside on anon-transitory computer-readable or processor-readable storage medium.Non-transitory computer-readable or processor-readable storage media maybe any storage media that may be accessed by a computer or a processor.By way of example but not limitation, such non-transitorycomputer-readable or processor-readable storage media may include RAM,ROM, EEPROM, FLASH memory, CD-ROM or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othermedium that may be used to store desired program code in the form ofinstructions or data structures and that may be accessed by a computer.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk, and Blu-raydisc where disks usually reproduce data magnetically, while discsreproduce data optically with lasers. Combinations of the above are alsoincluded within the scope of non-transitory computer-readable andprocessor-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes and/orinstructions on a non-transitory processor-readable storage mediumand/or computer-readable storage medium, which may be incorporated intoa computer program product.

The preceding description of the disclosed examples is provided toenable any person skilled in the art to make or use the presentdisclosure. Various modifications to these examples will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to some examples without departing from the spiritor scope of the disclosure. Thus, the present disclosure is not intendedto be limited to the examples shown herein but is to be accorded thewidest scope consistent with the following claims and the principles andnovel features disclosed herein.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope are approximations, the numerical values set forth inspecific non-limiting examples are reported as precisely as possible.Any numerical value, however, inherently contains certain errorsnecessarily resulting from the standard deviation found in theirrespective testing measurements at the time of this writing.Furthermore, unless otherwise clear from the context, a numerical valuepresented herein has an implied precision given by the least significantdigit. Thus a value 1.1 implies a value from 1.05 to 1.15. The term“about” is used to indicate a broader range centered on the given value,and unless otherwise clear from the context implies a broader rangearound the least significant digit, such as “about 1.1” implies a rangefrom 1.0 to 1.2. If the least significant digit is unclear, then theterm “about” implies a factor of two, e.g., “about X” implies a value inthe range from 0.5× to 2×, for example, about 100 implies a value in arange from 50 to 200. Moreover, all ranges disclosed herein are to beunderstood to encompass any and all sub-ranges subsumed therein. Forexample, a range of “less than 10” for a positive only parameter caninclude any and all sub-ranges between (and including) the minimum valueof zero and the maximum value of 10, that is, any and all sub-rangeshaving a minimum value of equal to or greater than zero and a maximumvalue of equal to or less than 10 (e.g., 1 to 4).

Some implementations of the present disclosure are described below inthe context of one or more hi-res Doppler LIDAR systems that are mountedonto an area (e.g., front, back, side, top, and/or bottom) of a personalautomobile; but, implementations are not limited to this context. Inother implementations, one or multiple systems of the same type or otherhigh resolution LIDAR, with or without Doppler components, withoverlapping or non-overlapping fields of view or one or more suchsystems mounted on smaller or larger land, sea or air vehicles, pilotedor autonomous, are employed. In other implementations, the scanninghi-res LIDAR is mounted at temporary or permanent fixed positions onland or sea.

1-20. (canceled)
 21. A light detection and ranging (LIDAR) system for avehicle, the LIDAR system comprising: a laser source configured toprovide an optical signal at a first signal power; a modulatorconfigured to modulate the optical signal from the laser source togenerate a modulated optical signal; an amplifier having a plurality ofgain levels, at which the amplifier is configured to amplify themodulated optical signal; and one or more processors configured to:based on the first signal power and a duty cycle of the optical signal,vary a gain level of the amplifier from the plurality of gain levels togenerate an amplified pulse signal, transmit the amplified pulse signalfrom the amplifier to an environment, receive a reflected signal that isreflected from an object, responsive to transmitting the amplified pulsesignal, and determine a range to the object based on an electricalsignal associated with the reflected signal.
 22. The LIDAR system ofclaim 21, wherein the one or more processors are configured to determinea second signal power based on the first signal power and the duty cycleof the optical signal, and the amplifier is configured to generate theamplified pulse signal at the second signal power.
 23. The LIDAR systemof claim 22, wherein the second signal power is different from the firstsignal power.
 24. The LIDAR system of claim 21, wherein the amplifiertransmits the amplified pulse signal via one or more optical elements.25. The LIDAR system of claim 21, wherein the one or more processors areconfigured to vary the gain level of the amplifier at random times orperiodically.
 26. The LIDAR system of claim 21, further comprising: anoptical switch coupled between the modulator and the amplifier, whereinthe one or more processors are configured to control the optical switchbetween an enabled state and a disabled state to cause the opticalswitch to generate a pulse signal based on the modulated optical signal.27. The LIDAR system of claim 26, wherein the optical switch isconfigured to send the pulse signal to the amplifier.
 28. The LIDARsystem of claim 26, wherein the one or more processors are configured tocontrol the optical switch between the enabled state and the disabledstate at random times or periodically.
 29. The LIDAR system of claim 21,wherein the one or more processors are configured to control an outputof the modulator between an enabled state and a disabled state to causethe modulator to generate a pulse signal based on the modulated opticalsignal.
 30. The LIDAR system of claim 29, wherein the one or moreprocessors are configured to control the output of the modulator betweenthe enabled state and the disabled state at random times orperiodically.
 31. An autonomous vehicle control system comprising one ormore processors, wherein the one or more processors are configured to:cause a laser source to provide an optical signal at a first signalpower; cause a modulator to modulate the optical signal from the lasersource to generate a modulated optical signal; cause an amplifier toamplify the modulated optical signal at a plurality of gain levels;based on the first signal power and a duty cycle of the optical signal,vary a gain level of the amplifier from the plurality of gain levels togenerate an amplified pulse signal; transmit the amplified pulse signalfrom the amplifier to an environment; receive a reflected signal that isreflected from an object, responsive to transmitting the amplified pulsesignal; and determine a range to the object based on an electricalsignal associated with the reflected signal.
 32. The autonomous vehiclecontrol system of claim 31, wherein the one or more processors areconfigured to: determine a second signal power based on the first signalpower and the duty cycle of the optical signal, and cause the amplifierto generate the amplified pulse signal at the second signal power. 33.The autonomous vehicle control system of claim 32, wherein the secondsignal power is different from the first signal power.
 34. Theautonomous vehicle control system of claim 31, wherein the one or moreprocessors are configured to vary the gain level of the amplifier atrandom times or periodically.
 35. The autonomous vehicle control systemof claim 31, wherein the one or more processors are configured tocontrol an optical switch between an enabled state and a disabled stateto cause the optical switch to generate a pulse signal based on themodulated optical signal, and the optical switch is coupled between themodulator and the amplifier.
 36. The autonomous vehicle control systemof claim 35, wherein the one or more processors are configured to causethe optical switch to send the pulse signal to the amplifier.
 37. Theautonomous vehicle control system of claim 35, wherein the one or moreprocessors are configured to control the optical switch between theenabled state and the disabled state at random times or periodically.38. The autonomous vehicle control system of claim 31, wherein the oneor more processors are configured to control an output of the modulatorbetween an enabled state and a disabled state to cause the modulator togenerate a pulse signal based on the modulated optical signal.
 39. Theautonomous vehicle control system of claim 38, wherein the one or moreprocessors are configured to control the output of the modulator betweenthe enabled state and the disabled state at random times orperiodically.
 40. A autonomous vehicle, comprising: a light detectionand ranging (LIDAR) system including: a laser source configured toprovide an optical signal at a first signal power; a modulatorconfigured to modulate the optical signal from the laser source togenerate a modulated optical signal; an amplifier having a plurality ofgain levels, at which the amplifier is configured to amplify themodulated optical signal; and one or more processors configured to:based on the first signal power and a duty cycle of the optical signal,vary a gain level of the amplifier from the plurality of gain levels togenerate an amplified pulse signal, transmit the amplified pulse signalfrom the amplifier to an environment, receive a reflected signal that isreflected from an object, responsive to transmitting the amplified pulsesignal, and determine a range to the object based on an electricalsignal associated with the reflected signal; at least one of a steeringsystem or a braking system; and a vehicle controller comprising one ormore processors configured to control operation of the at least one ofthe steering system or the braking system based on the range to theobject.